Picture frame



FIG. 1 is a perspective view of a picture frame showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top view thereof, the bottom, left side, and right side views being identical;

FIG. 4 is a perspective view of a second embodiment of a picture frame showing my new design;

FIG. 5 is a front view thereof; and,

FIG. 6 is a top view thereof, the bottom, left side, and right side views being identical.

The rear view of each embodiment forms no part of the claimed design. The broken lines shown in FIGS. 1, 3, 4, and 6 represent environmental subject matter and form no part of the claimed design. 

The ornamental design for a picture frame, as shown and described. 